AgNWs@SnO2/CuO nanocomposites for ultra-sensitive SO2 sensing based on surface acoustic wave with frequency-resistance dual-signal display

Surface acoustic wave (SAW) and metal-oxide-semiconductor sensor have been extensively studied for real-time monitoring of hazardous gases, such as sulphur dioxide (SO2). However, they often suffer from high operating temperature, long response/recovery time, low sensitivity and selectivity. In this work, a composite SO2 sensor with frequency-resistance dual-signal display has been designed based on SAW device and metal-oxide-semiconductor. Where silver nanowires@ stannic oxide/ cupric oxide (AgNWs@SnO2/CuO) with the heterogeneous SnO2/CuO structure and AgNWs acting as the support skeleton and catalytic material were used as sensitive materials. With a limit of detection (LOD) as low as 0.25 ppm, a short response/recovery time of 40 s/60 s, and a low operating temperature of 80 °C, the novel composite sensor offers good stability, reproducibility, accuracy, and selectivity. The high SO2 gas-sensing performance obtained was due to the n–p heterostructures of SnO2/CuO, the three-dimensional multi-vacancy structure of AgNWs, and the strong catalytic effect of Ag.